302系列的探測器都是常開的系統，有135華氏度（57攝氏度）和194華氏度（90攝氏度）兩種定溫度等級。 302-EPM-194 
302-EPM-135感溫棒
All 302 Series Detectors are normally open devices and are available in either 135°F (57°C) or 194°F (90°C) ratings. Each unit is constructed with a high expansion .040 anodized aluminum （氧化鋁）sensing shell and fine silver contacts which are hermetically seaLED to ensure reliable operation. Electrical Rating （額定電功率）6-28 VDC, 1 amp. (all models) 大發機電供感溫棒
302-135- Interior, Vertical Mounting Fixed Temperature 135°F Maximum Spacing - UL 50' x 50' 
302-194 - Interior, Vertical Mounting Fixed Temperature 194°F Maximum Spacing - UL 50' x 50' 
這款應該是室內使用 

302-ET-135 - All Weather, Vertical Mounting Fixed Temperature 135°F Maximum Spacing - UL 50' x 50' 
302-All Weather, Vertical Mounting Fixed Temperature 194°F Maximum Spacing - UL 50' x 50' 

這款是的環境使用 
302-AW-135 - Moisture and Dust Proof, Vertical Mounting Fixed Temperature 135°F Maximum Spacing - UL 50' x 50' 
302-AW-194 - Moisture and Dust Proof, Vertical Mounting Fixed Temperature 194°F Maximum Spacing - UL 50' x 50' 

這款是潮和塵